Document MJ6jvd5w7Gm7YzjxpyJDJY8KM

'- 1 540 CHAPTER 22 1956 Guide' ^ Table 3. Heat-carrying Capacity op Type L Copper Tubing . with Temperature Drop of 20 Deg* . . Nominal Tube Sizes i in. to 4 in., and Friction 60 to 720 milinches per foot. (A = . Capacity, Mbh. B = Velocity, inches per second) (One milinch equals O.OOl in.) Milinch Friction Loss peb Foot of Tube 720 600 480 360 300 240 180 150 120 90 75 60 H A B ' 8.9 23.6 7.8 20.8 7.0 5.9 18.6 15.7 5.4 14.4 4.7 < 3.9 12.5 10.4 3.6 9.6 3.1 8.2 2.7 7.2 2.3 2.1 6.1 .5.6 H- B 27.6 15.0 24.8 13.0 21.5 11.2 18.5 10.0 16.5 8.7 14.4 7.5 12.4 6.6 10.9 5.6 9.3 5.0 . 4.5 3.9 8.3, 7.4 6.4 H B 32.2 26.0 28.8 22.5 25.0 19.0 21.1 17.5 19.4 15.0 16.6 13.0 14.4 11.5 12.8 10.0 11;1 8.5 9.4 7.6 6.7 8.4 7.4 H A B 43.5 34.6 39.0 31.1 34.5 27.6 29.0 23.1 26.5 21.1 23.0 18.3 19.6 15.6 17.5 13.9 15.0 12.0 13.0 10.4 12.0 9.6 10.5 8.4 1 A B 93 43 84 39 74 34 63 29 57 27 50 42.5 23 20 38 18 34 28.5 16 13 26 23 12 11 1# ' B 160 145 128 107 97 49. 45 39 33 .30 85 26 73 22 65 20 57 48.5 18. 15 44' 39 .14 12 m; B 240 206 175 160 140 118 106 56 52 . 45 38 35 30 26 23 93 20 79 17 71 62. 15 13 2 A B 560 510 70 64 450 380 56 47 340 300 250 225 42 37 31 28 195 24 170 21 150 133 19 17 2H A B 1100 89 930 820 75 66 700 57 630 51 550- 470 44 38 420 ` 370 34 30 310 25 280 250 23 20 3 A B 1650 1500 1300 1100 94 85 74 62 990 '860 56 49 730 650 41 . 37 565 480 32 27 430 375 24 3V* B 105 2250 94 2000 84 1750 73 1500 63 1320 55 iioo- 1000 46 42 860 36 730 31 660' 580 28 A 3600 3200 2800 2400 2150 1900 1600 1440 1250 1150 950 840 B 116 103 .00 77 69 61 51 46 40 37 31 * For other temperature drope the pipe capacities may be changed coirrapondingly. For example, with temperature drop of 30 deg the capacities shown in thi6 table are to be multiplied by 1.5. spectively. These figures would also illustrate forced circulation if a pump or circulator were shown in the return line at the boiler. One-pipe gravity systems require very precise design owing to the small circulating head available. Also, circulation in them is slow, and .tem perature drop is large toward the end of the main, and consequently these systems are usually considered impractical. One-pipe forced. systems compared with gravity systems provide mbre rapid circulation, with consequent smaller temperature drop in mains and more uniform water temperature in all radiators, and are therefore preferred. Special flow and return fittings are available for improving the circulation to risers. Two-pipe systems, have separate flow and return mains. If the return main is.direct as shown in Fig. 5 the radiator at the end of the system has Pi Fl Fl, P, Pi P; [fjf F Fig: 4, One-Pipe System Fig. 5. A Two-Pipe Direct Return System Fig. 6. A Two-Pip Reversed Return System Hot Wfcterc Heating Systems 541- Table 4; Friction, (in- Milinches) ; op Central Circular Diaphragm Orifices- in Unions . ... {One milinch equals 0.001 in.) V. Diameteb of Velocity of Watbb in Pipe in Inches-peb Second " - (Inches) 2 3 | 4 j 6 | 8 | 10 | 12 | 18; | 24 . - 36 %-in. Pipe 0.25 0.30 0.35 0.40 0.45 0.50 0.55 1300 650 330 170 2900 1450 740 380 185 5000 2500 1300 660 330 155 75 11,300 6700 2900 1500 740 350 170 20,800 10,400 5200 2600 1300 620 300 32,000 16,000 8000 4000 2000 970 480 45,000 23,000 12,000 6800 2900 1400 700 57,000 26,000 13,000 6500 3200 ! 1600 47,000 24,000 12,000 5700 2800 53,000 27,000 13,000 6400 1-in Pipe 0.35 0.40 0.45 0.50 . 0.55 a. 60 0.65 0.45 0.50 0.55 0.60 0.65 0.70 0.75 900 2000 -460:: "1000 270 - 570 160 330 190 3500 rl800. 1000 580 . 330 200 120 7800 14,000 22,000 32,000 . :40ti0. :?72D0: :lQ00.: 17.000 2300 4100 6400 9300 1400 2300 3700 5400 750 1300 2200 3000 440 800 1300 1800 260 460 720 1100 .37,000 21,000 12,000 7000 4200 2400 .65,000 37,000 22,000 13,000 7400 4300 50,000 28,000 17,000 10,000 1000 660 430 280 190 2250 1450 950 630 420 285 190 1 yi-in. Pipe 4000 2600 1700 1100 750 510 330 8900 5800 3800 2500 1700 1150 750 16,000 10,400 6800 4400 3000 2000 1300 25,000 <16,400 10,500 6900 4700 .3100 2100 36,000 23,000 15,000 10,000 6700 4500 3000 i 53,000 34,000 22,000 15,000 10,000 6700 60,000 40,000 27,000 18,000 12,000 60,000 40,000 26,000 0.55 0.60 0.65 0.70 . 0.75 0.80 0.85 1/4`in- Pipe 850 1900 3300 7400 13,000 21,000 30,000 600 1300 2300 5400 8600 16,800 21,000 50,000 400 850 1500 3600 7200 10,400 14,000 30,000 53,000 260 600 1100 2600 4400 7000 10,000 21,000 39,000 180 400 760 1800 3000 5000 7000 14,000 28,000 300 540- 1200 2200 3200 5000 10,200 19,000 45,000 200 380 860 1600 2300 3000 7800 13,000 30,000 2-in. Pipe 0.70 0.80 0.90 1.00 1.10 120 1.30 890 1850 3500 470 975 1800 255 560 1000 160 340 610 214 375 195 7400 3900 2200 1320 850 460 275 14,000 7400 4200 2520 1600 950 525 22,300 11,700 6500 4000 2500 1360 980 33,000 17,000 9500 5800 3700 19101375 37,000 20,500 12,500 7900 4200 3100 38,000 23,000 14,000 8100 4400 49,000 30,000 16.800 8850 Note.--The losses of head for the orifices in the lH-in. and 2-in. pipe were calculated from those in the jailer pipes, the calculations being based on the assumption that, for any given velocity, the loss of head a function of the ratio of the diameter of the pipe to that of the orifice. This had been found to be practically true in the teste to determine the losses of head in orifices in -in., 1-in., and lM-in. pipe, conducted by the Texas Engineering Experiment Station, and also in the tests to determine the losses of head in on* fieea in 4-in., 6-in., and 12-in. pipe, conducted by the Engineering Experiment Station of tie Uniwmtp of l&inoit, (Bulletin 109, Table 6, p. 38, Davis and Jordan).